1. Field of the Disclosure
The present disclosure generally relates to imaging systems and, more particularly, to a system and method to perform imaging and control using an embedded imaging system.
2. Brief Description of Related Art
There are many types of automated equipment that count and dispense pharmaceutical pills in pharmacies, hospitals and central fill facilities for end use. These types of pill counting and dispensing machines use thru-beam optical sensors to count pills as they are dispensed. Some of the machines also make crude attempts to detect pill fragmentation using multiple thru-beam optical sensors.
Pharmaceutical companies sometimes use vision-based applications to examine pills and make decisions about pill quality. However, the vision-based inspection requirements of a pharmaceutical production facility are significantly different from those of a retail pill counting and dispensing machine that would be used in a central fill facility, mail order pharmacy, hospital or other health care related institution. As a result, the pharmaceutical production facility typically uses a different type of vision-based inspection mechanism. In a pharmaceutical production facility, typically there are many more of the same type of pills, all moving at much higher speeds. These factors push the production facility image processing requirements to a level where high end vision processors are required and there is no excess processing time left to handle real time processing of I/O (Input/Output) data within the camera sensor itself. As a result, the vision mechanism used in a pharmaceutical production facility is not an embedded piece of equipment. It is a bolt-on, external sensor that provides live video feed that is externally processed using a powerful external processing system. All I/O control (e.g., movement of a robot arm to grab a pill) and related I/O decision making processes are handled external to the vision mechanism. In summary, the pharmaceutical production facility vision mechanism is of a different type that cannot be used in the pill counting and sorting machines used in pharmacies, hospitals, central fill or mail order facilities.
Although vision-based inspection mechanisms do exist for use in automation applications, all of these systems cost on average $4,000. These systems fall into the four categories described below.
The first category consists of a large camera package which is connected to an external PC (Personal Computer) or image processing and I/O control unit. The PC or remote processing and control unit performs the image processing and I/O control functions. These systems are much too large to be used in an embedded application. In fact, these mechanisms are larger than most of the pill counting and inspection products.
The next category consists of a camera package that interfaces to the world using a communications port (such as USB (Universal Serial Bus), Firewire or Camera Link). The communications port is used to output images and provide access to the internal image processing algorithm. An external trigger is used to initiate image capture. The purpose of this system is to output processed stop action images. However, these systems are unsuitable for many embedded applications because external hardware is required to evaluate the processed image and/or initiate I/O control of external devices based on the results of the evaluation. This type of vision mechanism usually uses large adjustable stock lenses and is encased in a metal box which makes the unit physically too large for embedded applications.
The third category consists of dedicated vision based sorting devices that are comprised of a camera, an internal hardware-coded image processing algorithm and between 6 and 8 bits of digital I/O. The devices compare the captured image to a reference and output 6 to 8 bits of pass/fail criteria on digital I/O. No other I/O exists. The I/O output is an image processing result as opposed to an I/O controller output. Although this image processor output may be used to perform rudimentary control, the device does not contain a controller and there are no resident controller algorithms. These devices are typically too large for embedded use and they do not have an I/O controller or controller programming capability, only several bits of image pass/fail results, which may or may not be usable for process control. Although the image processor in such devices uses variables, which a user may set, the image processing is hardware coded and cannot be altered.
The last category includes products sold by DVT sensors, which are advertised as “smart camera sensors.” These vision sensors can control camera lighting. They perform both image processing and limited I/O control. These products provide 8 bits of direct digital I/O and access to additional I/O data through an Ethernet or Fieldbus connection. These 8 bits of digital I/O are primarily used to report vision algorithm results, control camera lighting, and provide camera event triggering. Although these vision sensors are physically small enough to fit in most embedded applications, a closer examination of the capabilities and characteristics of such smart camera sensors shows that they are incompatible with most embedded applications. Smart camera sensors are similar to PC based vision applications, downsized through the use of newer technology, until the package fits in the palm of the hand. However, the smart camera sensors still primarily remain vision sensors that happen to be small, but they lack real-time I/O processing and I/O control capabilities, as will be explained later.
Some other devices with image capturing capabilities include picture phones and digital cameras. Picture phones employ continuous scan imaging sensors. This technology is incompatible with capturing high resolution, real time, moving images (e.g., image of pills on a conveyor belt in a pharmaceutical production facility) without unacceptable blurring unless the moving object is relatively far away. This is because pictures of a moving object will have good resolution only if the object is sufficiently far away so that the object speed is slow relative to both the electronic shutter speed and the camera sensor scan speed. Some digital cameras employ image sensors with a global shutter. This technology is compatible with capturing high resolution, real time, moving images without unacceptable blurring, if the camera has electronic shutter speeds that are fast enough to “freeze” the object motion. Most digital camera sensors have electronic shutter speeds that are faster than the speeds of shutters in picture phones, but the image sensors in digital cameras are still usually an order of magnitude or more too slow for most applications. In the case of taking an image of a moving pill, the digital camera sensor might be able to do the job if the camera is moved slow and steady enough to enable the use of the camera's slower electronic shutter speeds.
However, a picture phone or digital camera cannot be programmed to perform real time image processing that will result in an output that can be used to control image process related real time I/O. Both picture phones and digital cameras employ dedicated electronics to adjust the image in ways that are more appealing to the human eye. They perform tasks such as balancing the light and dark areas in the image, removing red eye and making color corrections. The output is then placed in storage and/or made available for display. These devices do not possess a programmable microprocessor or a DSP (Digital Signal Processor) that can be programmed to perform real time image processing that would yield an output that can be used by a real time I/O controller. This means that these devices have the ability to generate a nice picture for a human to look at, but they do not possess the ability to draw any conclusions about the picture in real time or otherwise.
As to real time I/O control and interface, it is observed that the I/O control and interface on a picture phone consists of a GUI (General User Interface) that can be manipulated by the user/operator to send the image to a remote location. This is not a real time I/O control and interface hardware, and it cannot be adapted to perform this function. Digital cameras have a variety of I/O, none of which can accomplish real time process control. Usually the camera has a manual motorized zoom, an interface to facilitate internal image storage, and an interface that enables image download to an external device such as a printer or computer. These are not real time processes and the hardware that performs these processes does not have an architecture that supports a real time requirement.
It is therefore desirable to develop a real time embedded vision system wherein all of the image capture, image processing, I/O controller and I/O interface hardware fits inside a package that is small enough to reside inside most machines that would employ such a device. It is also desirable for all of the image capture and image processing, as well as all the I/O processing and I/O control, to be in real time and for the embedded vision system to run off the available power.